Policemen collect evidence on December 21, 2014 in Dijon on the site where a driver shouting 'Allahu Akbar' ('God is great') ploughed into a crowd injuring 11 people, two seriously, a source close to the investigation said.

A driver deliberately slammed his car into crowds around the city of Dijon in eastern France on Sunday, raising concerns at a time when Islamic extremists are calling for attacks in France.

The Sunday night rampage came a day after a knife attack on police in another French town that counter-terrorist police are investigating. The government said the motive for Sunday's attack was unclear.

The government stepped up security measures for police and other authorities.

In Sunday's incident, police arrested the driver after he injured at least 11 people, the Interior Ministry said in a statement.

The Islamic State group and other terrorist organizations have repeatedly called for attacks against France, notably because of the French military's participation in U.S.-led airstrikes in Iraq. Some extremists have specifically suggested that anyone angry at the French government could use weapons easily at hand — such as cars or knives — to stage "lone wolf" attacks.

The Interior Ministry said the driver in Sunday's car attack, a 40-year-old driving a Renault Clio, was known to police for minor offences in the 1990s.

Police union official Michel Bonnet said on BFM television that some witnesses apparently heard the driver say "Allahu Akbar," or "God Is Great," and refer to the "children of Palestine."

In an indication of how seriously the government is taking the incident, Interior Minister Bernard Cazeneuve was to head to Dijon on Monday.

Ministry spokesman Pierre-Henry Brandet said it was too early to say whether there was any connection between the Sunday car attack and the knife attack in Joue-les-Tours in central France on Saturday.

In the Saturday incident, two police officers were seriously injured and the attacker was killed, according to the ministry. While the motive remains uncertain, anti-terrorism police are involved in the investigation.